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Since you’re here, you probably reach the point in which standard annotations like @NotNull or @Size don’t meet your expectations. Fortunately, I have good news for you. Creating a custom validation annotation is pretty easy. In this post, you will learn how to create a custom constraint annotation and a corresponding validator class. You will also see how to use Spring beans inside a custom validator.
Let’s just right into it.
All built-in JSR 303 constraint annotations are intended to verify particular fields of our data classes. Yet, it is not unusual that several fields are connected to each other and should be checked as a unity.
For instance, a field can be required only if another field is set. @NotNull won’t work in such case as there is no way to introduce the condition logic. In this post you will learn how to write a validator applicable to multiple class fields.
Some validation constraint can be applied to several different types. For instance the @Size annotation works with collections, arrays, and strings. This post is a guide on how to create a validation constraint which can be applied to different data types just like the aforementioned @Size annotation.
Continue reading “Custom validation annotation for multiple types”
In the previous post you could learn how to create a basic custom constraint annotation compatible with the Bean Validation standard. This demo will extend the former post by explaining how to create constraints which are more flexible due to parameters defined for particular use cases. If you’re totally unfamiliar with the topic, I refer you to the aforementioned post to grasp the essentials. Otherwise, just keep reading.
Continue reading “Custom parametrized validation annotation”